Achieving high strength and ductility in selective laser melting Ti-6Al-4V alloy by laser shock peening

• Published in: Journal of alloys and compounds Vol. 899; p. 163335
• Main Authors: Lv, Jiming, Luo, Kaiyu, Lu, Haifei, Wang, Zhao, Liu, Jiajun, Lu, Jinzhong
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 05.04.2022; Elsevier BV
• Subjects: Compressive properties; Dislocation density; Ductility; Electron backscatter diffraction; Elongation; Grain refinement; Lamellar structure; Laser beam melting; Laser shock peening; Laser shock processing; Lasers; Mechanical properties; Microstructure; Peening; Rapid prototyping; Residual stress; Selective laser melting; Tensile property; Ti-6Al-4V titanium alloy; Titanium base alloys; Ultimate tensile strength; Laser shock peening; Tensile property; Selective laser melting; Microstructure; Residual stress; Ti-6Al-4V titanium alloy
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2021.163335

•Effect of LSP on tensile behavior of the SLMed Ti6Al4V alloy was studied.•LSP generated compressive residual stress in surface layer of SLMed sample.•Dislocations and nano twins were induced in SLMed sample by LSP.•LSP realized excellent combination of strength and ductility in SLMed sample.•The mechanism of the tensile property enhancement by LSP was revealed. [Display omitted] In this work, the influences of laser shock peening (LSP) on the residual stress state, microstructures and mechanical properties of Ti-6Al-4V alloy fabricated by selective laser melting (SLM) were researched. Particularly, the microstructural evolution before and after LSP was clarified using electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) observations. The results showed that the residual stress was adjusted from tensile to compressive state. Furthermore, high-density dislocations and a great number of parallel nano mechanical twins (nano-MTs) were promoted in the coarse lamellar α' structures, contributing to the grain refinement. The ultimate tensile strength and elongation of the SLM-manufactured (SLMed) Ti-6Al-4V alloy increased by approximately 14.3% and 18.3% after LSP treatment, respectively. Finally, the dominant mechanism of tensile property enhancement by LSP was revealed. High levels of compressive residual stress and grain refinement of the α' structures induced by LSP realized the excellent combination of strength and ductility.